The dependence of constituent transport on chemistry in a two-dimensional model of the middle atmosphere

The transport of trace species by waves is affected by their production and/or destruction by photochemical processes. For this reason the transport or diffusion matrices used in two-dimensional models should be different for each constituent. This paper describes a method for altering the meridional and vertical dynamical transport coefficients for use with photochemically active species. The transport represents the net meridional eddy flux by planetary waves and the net vertical eddy flux by gravity waves. Output from integrations using the control (species independent) and chemical eddy transport coefficients are compared. The change in the meridional (planetary wave) transport results in modest, but nevertheless significant, changes in the distribution of trace species. In many cases, for example odd oxygen and nitric acid, the model changes bring the distributions closer to those observed. In contrast, the incorporation of the chemical eddy effect into the gravity wave transport has almost no effect on any of the model fields